Catalyst comprising a phosphorous modified zeolite and having partly an ALPO structure

ABSTRACT

A catalyst can include a phosphorus modified zeolite having partly an ALPO structure. The ALPO structure can be determined by a signal between 35-45 ppm in  27 Al MAS NMR spectrum. The zeolite can include at least one ten member ring in the structure thereof. The catalyst can also include a binder and one or more metal oxides. The catalyst can be used in processes in the presence of steam at high temperatures, such as temperatures that are above 300° C. and up to 800° C. The catalyst can be used in alcohol dehydration, olefin cracking, MTO processes, and alkylation of aromatic compounds with olefins and/or alcohols.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of PCT/EP2012/064581, filed on Jul.25, 2012, which claims priority from EP 11176394.2, filed on Aug. 3,2011.

FIELD OF THE INVENTION

The present invention relates to a catalyst comprising a phosphorusmodified zeolite, said phosphorus modified zeolite having partly an ALPOstructure. It also relates to a method for making said catalyst. Thismodified zeolite is of interest in processes wherein said zeolite isoperated in presence of steam at high temperature. By way of example onecan cite,

the alcohol dehydration to convert at least an alcohol into thecorresponding olefin,

the cracking of C4+ olefins (also known as OCP, olefins conversionprocess) to make a mixture of ethylene and propylene,

the cracking of methanol or dimethylether (also known as MTO) to producelight olefins such as ethylene and propylene as well as heavyhydrocarbons such as butenes, alkylation of aromatic compounds witholefins and alcohols to produce para-xylene, ethylbenzene, cumene etc.

BACKGROUND OF THE INVENTION

An efficient catalyst is a key in industrialization of dehydration ofalcohols as well as in the other above processes. One of the earlycatalysts employed for the dehydration of ethanol was alumina. Thiscatalyst is relatively cheap but needs low space velocity and highreaction temperature and makes a lot of ethane, which needs to beseparated. Zeolites, particularly phosphated zeolites, solve a problemwith catalyst activity and provide with ethylene fraction close topolymer grade. Catalysts comprising a phosphorus modified zeolite (thephosphorus modified zeolite is also referred as P-zeolite) are known.The following prior arts have described various methods to make saidcatalysts.

US 2006 106270 relates to the use of a dual-function catalyst system inthe hydrocarbon synthesis reaction zone of an oxygenate to propylene(OTP) process that operates at relatively high temperatures preferablywith a steam diluent and uses moving bed reactor technology. Thedual-functional catalyst system comprises a molecular sieve havingdual-function capability dispersed in a phosphorus-modified aluminamatrix containing labile phosphorus and/or aluminum anions. It isexplained that the hydrothermal stabilization effect that is observedwhen this phosphorus-modifed alumima matrix is utilized is caused bymigration or dispersion of phosphorus and/or aluminum anions from thismatrix into the bound molecular sieve. These anions are then availableto repair, anneal and/or stabilize the framework of the molecular sieveagainst the well-known dealumination mechanism of molecular sieveframework destruction or modification that is induced by exposure tosteam at temperatures corresponding to those used in the OTP reactionzone and in the regeneration zone.

U.S. Pat. No. 5,231,064 is directed to a fluid catalyst comprising clayand a zeolite, at least one of which has been treated with a phosphoruscontaining compound, for example ammonium dihydrogen phosphate orphosphoric acid, and which is spray dried at a low pH, preferably lowerthan about 3. Said catalysts are deemed to advantageously exhibitreduced attrition.

EP 511013 A2 provides an improved process for the production of C2-C5olefins from higher olefinic or paraffinic or mixed olefin and paraffinfeedstocks. In accordance with this prior art, the hydrocarbon feedmaterials are contacted with a particular ZSM-5 catalyst at elevatedtemperatures, high space velocity and low hydrocarbon partial pressureto produce lower olefins. The catalysts is treated with steam prior touse in the hydrocarbon conversion. The preferred method is to heat thecatalyst at 500 to 700° C., preferably 550 to 600° C., under 1 to 5atmospheres, preferably 1.5 to 3 atmospheres steam for 1 to 48 hours,preferably 15 to 30 hours. The active catalyst component isphosphorus-containing ZSM-5 having a surface Si/Al ratio in the range20-60. Preferably, the phosphorus is added to the formed ZSM-5 as byimpregnating the ZSM-5 with a phosphorus compound in accordance with theprocedures described, for example, in U.S. Pat. No. 3,972,832. Lesspreferably, the phosphorus compound can be added to the multicomponentmixture from which the catalyst is formed. The phosphorus compound isadded in amount sufficient to provide a final ZSM-5 composition having0.1-10 wt. % phosphorus, preferably 1-3 wt. %.

The phosphorus-containing ZSM-5 is preferably combined with knownbinders or matrices such as silica, kaolin, calcium bentonite, alumina,silica aluminate and the like. The ZSM-5 generally comprises 1-50 wt. %of the catalyst composition, preferably 5-30 wt. % and most preferably10-25 wt. %. There is no introduction of metals such as Ca in thecatalyst.

EP 568913 A2 describes a method for preparing a ZSM-5 based catalystadapted to be used in the catalytic conversion of methanol or dimethylether to light olefins, wherein it comprises the following consecutivesteps:

-   -   mixing a zeolite ZSM-5 based catalyst with silica sol and        ammonium nitrate solution,    -   kneading, moulding, drying and calcining the mixture,    -   exchanging the modified zeolite with a solution of HCl at 70-90°        C.,    -   drying and calcining the H-modified zeolite,    -   impregnating the H-modified zeolite with phosphoric acid under        reduced pressure,    -   drying and calcining the P-modified zeolite,    -   impregnating the P-modified zeolite with a solution of rare        earth elements under reduced pressure,    -   drying and calcining the P-rare earths-modified zeolite,    -   hydrothermally treating the P-rare earths-modified zeolite at        500-600° C. with water vapour, and    -   calcining the modified zeolite.

WO 03 020667 relates to a process of making olefin, particularlyethylene and propylene, from an oxygenate feed, comprising contacting anoxygenate feed with at least two different zeolite catalysts to form anolefin composition, wherein a first of the zeolite catalysts contains aZSM-5 molecular sieve and a second of the zeolite catalysts contains azeolite molecular sieve selected from the group consisting of ZSM-22,ZSM-23, ZSM-35, ZSM-48, and mixtures thereof. The ZSM-5 can beunmodified, phosphorus modified, steam modified having a microporevolume reduced to not less than 50% of that of the unsteamed ZSM-5, orvarious mixtures thereof. According to one embodiment, the zeolite ismodified with a phosphorus containing compound to control reduction inpore volume. Alternatively, the zeolite is steamed, and the phosphoruscompound is added prior to or after steaming. The amount of phosphorus,as measured on an elemental basis, is from 0.05 M.% to 20 wt. %, andpreferably is from 1 wt. % to 10 wt. %, based on the weight of thezeolite molecular sieve. Preferably, the atomic ratio of phosphorus toframework aluminum (i.e. in the zeolite framework) is not greater than4:1 and more preferably from 2:1 to 4:1. Incorporation of a phosphorusmodifier into the catalyst of the invention is accomplished, accordingto one embodiment, by contacting the zeolite molecular sieve eitheralone or the zeolite in combination with a binder with a solution of anappropriate phosphorus compound. The solid zeolite or zeolite catalystis separated from the phosphorus solution, dried and calcined. In somecases, the added phosphorus is converted to its oxide form under suchconditions. Contact with the phosphorus-containing compound is generallyconducted at a temperature from 25° C. to 125° C. for a time from 15minutes to 20 hours. The concentration of the phosphorus in the zeolitemay be from 0.01 wt. % to 30 wt. %. This prior art discloses anon-formulated P-ZSM-5.

WO 2009 022990 A1 describes a catalyst composition for dehydration of analcohol to prepare an alkene. The catalyst composition comprises acatalyst and a modifying agent which is phosphoric acid, sulfuric acidor tungsten trioxide, or a derivative thereof. There is no binder.

EP 2348004 A1 relates to the dehydration of ethanol to make ethylene andconversion of methanol to make a mixture of olefins (MTO). The catalystis made by the following process: A ZSM-5 is steamed, P is introduced bycontacting the steamed zeolite with an H3PO4 solution under refluxconditions, the P modified zeolite is extruded with a binder, calcium isintroduced and the resulting catalyst is steamed two hours at 600° C.Alternatively the binder can be introduced before the introduction of P.

WO 2009-098262 A1 relates to the dehydration of ethanol to makeethylene. The catalyst is made by the following process: A ZSM-5 issteamed, P is introduced by contacting the steamed zeolite with an H3PO4solution under reflux conditions, the P modified zeolite is extrudedwith a binder, there is no final steaming. There is no introduction ofcalcium.

EP 2082802 A1 relates to various petrochemical processes, thedehydration of alcohols to make an olefin having the same number ofcarbon atoms as the alcohol is not cited. Among the cited processes arethe cracking of olefins and the conversion of oxygenates, e.g. methanolto make a mixture of ethylene, propylene, butenes and varioushydrocarbons. The catalyst is made by the following process: A ZSM-5 issteamed, the steamed zeolite is extruded with a binder, P is introducedby contacting the steamed zeolite with an H3PO4 solution under refluxconditions, calcium is introduced and the resulting catalyst is steamedtwo hours at 600° C.

U.S. Pat. No. 4,356,338 relates to various petrochemical processes, thedehydration of alcohols to make an olefin having the same number ofcarbon atoms as the alcohol is not cited. The zeolite (ZSM-5) may becombined with a binder and is treated by a P containing component orsteam or both steam and P containing component. There is no introductionof metals such as Ca in the catalyst.

The phosphorus-modified alumina composite is known in prior art and isuseful as a binder as well as a catalyst support for various catalyticreactions. This type of binder brings a good mechanical resistance tothe catalyst particle and can be easily shaped in any form. This binderis used for manufacturing of catalysts by extrusion, oil-drop orspray-drying methods.

Aluminium phosphates exist in different atomic Al/P-ratios. In thecomposition AlPO4, they are isoelectronic with SiO2 and consist ofalternating A104/2- and PO4/2-tetrahedra. Six among the known, densecrystal modifications of AlPO4 are isostructural with modifications ofsilica; tridymite is one of these. In addition, many AlPO4 molecularsieves are known, of which some are isostructural with zeolites.

In the shaping of catalysts, however, aluminium phosphates have mostlybeen used as amorphous solids or hydrogels, so far. They exhibit acidicproperties at atomic ratios Al/P>1, and even more pronounced as hydrogenphosphates with Al/P<1. With a composition Al/P˜1, the acid strength ofterminal OH-groups is said to be similar or even somewhat lower than inthe case of γ-Al2O3. Aluminium phosphates as such have been applied asacidic catalysts in the dehydration of alcohols to ethers U.S. Pat. No.5,753,716.

On the contrary, the amorphous stoichiometric AlPO is almost neutral.

The examples of AlPO preparation is given by U.S. Pat. No. 4,629,717.Typically, the AlPO binders with amorphous phases are prepared by thetreatment of pseudo-boehmite with phosphoric acid followed by additionof ammonia or by direct blending of alumina or aluminum salts withsources of phosphorous. A number of academic articles, for examples,Applied Catalysis A: General 374 (2010) 18-25; Applied Catalysis A:General 328 (2007) 210-218, Catalysis Communications 7 (2006) 745-751,Applied Catalysis A: General 391 (2011) 254-260, addresses to the topicof zeolite shaping with phosphorus-modified alumina composite.

In the cases reported in prior art, the aluminum source used formanufacturing of aluminium phosphates was a component of binder andwasn't a part of crystalline structure of zeolite. Often, the aluminumphosphate was produced by treating of the external source of aluminum(alumina or aluminum salts) by a source of phosphorous followed byblending with zeolite. Sometimes, the different types of alumina or thesalt's of aluminum were blended with phosphorous and zeolitesimultaneously.

The current invention discloses a method to produce phosphorus modifiedzeolite having partly an ALPO structure formed from zeolitic aluminumatoms. It is worth to be noted that the aluminum atoms located in thestructure of zeolite do not necessary react with a source of phosphorousto form such ALPO phase. It might be necessary to partially activate thealuminum atoms to facilitate the reaction.

It has now been discovered a new catalyst comprised a P modifiedzeolite.

BRIEF DESCRIPTION OF THE INVENTION

It is evident that the industrial operations cannot be based on acatalyst, which undergoes discontinuous changes in activity andselectivity and will reach the equilibrated state only after severaltens or hundreds of reaction-regeneration cycles.

It was found that the changes in the catalyst structure become limitedif the most part of aluminum atoms are in form of ALPO phase. ALPO phaseshows a signal between 34-45 ppm in the ²⁷Al MAS NMR spectrum. So, ifthe essential part of Al-atoms shows the signal in the range 34-45 ppm,the equilibration state of the catalyst has been achieved and furtherchanges will be negligible.

A treatment of crystalline MFI zeolite with a source of phosphorous(even using phosphorus acids) won't lead to the extraction of theAl-atoms from network (tetrahedral aluminum) and formation of the ALPOphase, meaning that the catalyst will still be very sensitive to thesteam treatment and may undergo further changes during the reactions inpresence of steam.

Only a very severe steaming makes the Al atoms from the zeoliteframework reacting with phosphorous. At the exception of FCC process,the catalysts aren't usually subjected to such a severe steaming duringthe normal operation. This means that the catalyst may undergo furtherchanges during the reactions in presence of steam. This is one of thereasons of a great amount of patents but still a limited industrialapplication of these materials beyond the FCC field. FCC means Fluid BedCatalytic Cracking, it is used to crack heavy petroleum fractions toproduce lighter components. Usually the catalyst comprises, the totalbeing 100%, 1.5 to 15 w % of a P modified zeolite and 98.5 to 85 w % ofa mixture of a binder and a Y zeolite. An FCC catalyst is described inEP 1 797 951 A1.

The present invention relates to a catalyst comprising a phosphorusmodified zeolite, said phosphorus modified zeolite having partly an ALPOstructure, wherein,

the catalyst comprises a P-modified zeolite and a binder,

the zeolite comprises at least one ten members ring in the structure,

optionally the catalyst comprises one or more metals,

the ALPO structure is determined by a signal between 35-45 ppm in ²⁷AlMAS NMR spectrum.

The above mentioned metal can be a metal oxide.

In an embodiment, the above mentioned binder is substantially free ofalumina or alumina salts. So, the most part of Al atoms in ALPO phaseoriginate from the zeolite or from other part of binder, for exampleclays.

ALPO specie in P-ZSM-5 zeolites can be identified and quantified bycombining quantitative MAS NMR spectroscopy with high resolutionmultiple quantum MQ MAS NMR (L. Frydman et al. JACS, 117, 1995, 5367)and ²⁷Al—³¹P HETCOR techniques. After an extensive examination ofseveral possible approaches, we have determined that the quantitativeestimates of various ²⁷Al intensities in phosphorous modified zeolitescan be best obtained by combining the analysis of MQMAS and MAS spectra(J.-P. Amoureux, M. Pruski, in: D. M. Grant, R. K. Harris (Eds.),Encyclopedia of Nuclear Magnetic Resonance, vol. 9, John Wiley & Sons,Chichester, 2002, pp. 226-251). The MQMAS spectra, which are notinherently quantitative, can be used to determine the isotropic chemicalshift and the quadrupolar parameters for different sites. This providesa starting set of parameters for fitting the MAS spectra in order toobtain the correct intensities. We note that the analysis of MAS resultscould be performed using a simulation program described in (D. Massiotet al Magn. Reson. Chem. 40 (2002) 70), considered the distribution ofchemical shift and quadrupolar parameters. The ²⁷Al—³¹P HETCOR spectraof sample show correlations of phosphorus with Al through space (C. A.Fyfe, H. Grondey, K. T. Mueller, K. C. Wong-Moon, T. Markus, J. Am.Chem. Soc. 114 (1992) 5876).

Combination of the MQMAS & ²⁷Al-³¹P correlation analysis are especiallyuseful if we have to separate ALPO species from extra framework pentacoordinated alumina are distorted tetra coordinated alumina. So, thesetechniques help to identify ALPO species.

The present invention also relates to the use of the above catalystwherein said catalyst is operated in presence of steam at hightemperature. “high temperature” means above 300° C. and up to 800° C. Byway of example one can cite, the alcohol dehydration to convert at leastan alcohol into the corresponding olefin, the olefin cracking to makelighter olefins, the MTO and the alkylation of aromatic compounds witholefins and/or alcohols to produce, by way of example, para-xylene,ethylbenzene, cumene etc.

Said catalyst can be made by the following methods. In a firstembodiment the zeolite is mixed with the binder, shaped to a catalyst,then P is introduced. In a second embodiment P is introduced in thezeolite, the P modified zeolite is mixed with the binder, then shaped toa catalyst.

The present invention relates, in a first embodiment, to a method tomake a phosphorus modified zeolite, having partly an ALPO structure,comprising the following steps in this order,

a) providing a zeolite comprising at least one ten members ring in thestructure, optionally steaming said zeolite,

b) mixing said zeolite of step a) with at least a component selectedamong one or more binders and shaping additives, then shaping saidmixture,

c) optionally making a ion-exchange,

d) optionally steaming the shaped catalyst, optionally before step c),

e) introducing phosphorus on the catalyst to introduce at least 0.1 wt %of phosphorus,

f) optionally introducing a metal, optionally simultaneously with stepe),

g) optionally washing the catalyst,

h) optionally calcinating the catalyst,

i) steaming the catalyst, also referred to as the equilibration step.

In an embodiment the shaped zeolite (or molecular sieve) of step b)contains less than 1000 wppm of sodium.

In an embodiment the shaped zeolite (or molecular sieve) of step b)contains less than 1000 wppm of sodium, less than 1000 wppm of potassiumand less than 1000 wppm of iron.

In an embodiment the shaped zeolite (or molecular sieve) of step b)contains less than 100 wppm of sodium.

In an embodiment the shaped zeolite (or molecular sieve) of step b)contains less than 100 wppm of sodium, less than 100 wppm of potassiumand less than 500 wppm of iron.

In a second embodiment the phosphorus is introduced in the zeolite priorto the mixing with the binder.

The present invention relates, in a second embodiment, to a method tomake a phosphorus modified zeolite, having partly an ALPO structure,comprising the following steps in this order,

a) providing a zeolite comprising at least one ten members ring in thestructure, optionally making a ion-exchange,

b) optionally steaming said zeolite,

c) introducing phosphorus on the zeolite to introduce at least 0.1 wt %of phosphorus,

d) mixing said zeolite of step c) with at least a component selectedamong one or more binders and shaping additives,

e) shaping said mixture,

f) optionally introducing a metal, optionally simultaneously with stepd),

g) optionally washing the catalyst,

h) optionally calcinating the catalyst,

i) steaming the catalyst, also referred to as the equilibration step.

In an embodiment the zeolite (or molecular sieve) prior to step c)contains less than 1000 wppm of sodium.

In an embodiment the zeolite (or molecular sieve) prior to step c)contains less than 1000 wppm of sodium, less than 1000 wppm of potassiumand less than 1000 wppm of iron.

In an embodiment the zeolite (or molecular sieve) prior to step c)contains less than 100 wppm of sodium.

In an embodiment the zeolite (or molecular sieve) prior to step c)contains less than 100 wppm of sodium, less than 100 wppm of potassiumand less than 500 wppm of iron.

The present invention also relates to the use of the catalyst madeaccording to the above method in processes wherein said catalyst isoperated in presence of steam at high temperature. “high temperature”means above 300° C. and up to 800° C. By way of example one can cite,the alcohol dehydration to convert at least an alcohol into thecorresponding olefin, the olefin cracking to make lighter olefins, theMTO and the alkylation of aromatic compounds with olefins and/oralcohols to produce, by way of example, para-xylene, ethylbenzene,cumene etc.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a ²⁷M MAS NMR spectrum of a phosphated sample.

FIG. 2 shows a phosphated sample that shows relatively sharp andintensive resonance at 39 ppm representing an AlPO phase.

DETAILED DESCRIPTION OF THE INVENTION

Hereunder is explained the description of the catalyst comprising aphosphorus modified zeolite, said phosphorus modified zeolite havingpartly an ALPO structure.

As regards the zeolite, it is described further in the explanations ofthe method to make said catalyst.

As regards the binder, it is described further in the explanations ofthe method to make said catalyst.

As regards the P-modified zeolite and the binder, advantageously theproportion of the zeolite is from 5 to 95 w % of the catalyst. Thecatalyst comprises the zeolite and at least a component selected amongone or more binders and shaping additives. The amount of zeolite whichis contained in the catalyst ranges more advantageously from 15 to 90weight percent of the total catalyst, preferably 20 to 85 weight percentof the catalyst.

The amount of phosphorus on the catalyst can be from 0.5 to 30 wt %, butpreferably from 0.5 to 9 w %.

As regard the metal, it can be one or more metals, advantageously saidmetals are selected among alkaline earth or rare earth metals. Thealkaline earth or rare earth metal M is preferably selected from one ormore of: Mg, Ca, Sr, Ba, La, Ce. More preferably, M is an alkaline earthmetal. Most preferably, M is Ca. Particularly in the case ofP-modification via steaming and leaching, M can be a rare earth metalsuch as La and Ce.

As regards the determination and quantification of the ALPO structure,it has been made by a ratio of the signals in ²⁷Al MAS NMR spectum. Thecontent of said ALPO structure in the catalyst can be up to 99% andadvantageously ranges from 10 to 98 w %.

The structure of the aluminum-containing species can be probed bysolid-state NMR methods.

Solid-state magic angle spinning (MAS) NMR experiments are performed onBruker Avance 500 spectrometer, with a 4 mm zirconia MAS probe at arotation rate of 15 kHz. In order to obtain quantitative MAS spectra, asingle pulse excitation was applied using a short pulse length 0.6 psec.Each spectrum resulted from 5000 scans separated by a 0.5 sec delay.Chemical shifts of the ²⁷Al spectra were referenced to AlCI₃ solution(0.1 M, (0 ppm).

In case if there is only zeolitic aluminum source in the catalyst, thecontent of the ALPO phase can be estimated directly by a surface ratioof the signal at 35-45 ppm in ²⁷Al MAS relative to a total surface ofthe spectrum between −50 and 100 ppm.

In case if the binder contains aluminum and phosphorous the content ofthe ALPO phase in zeolite can be estimated by a surface ratio of thesignal at 35-45 ppm in ²⁷Al MAS relative to a total surface of thespectrum between −50 and 100 ppm after the subtraction of the signalintensities of binders.

Hereunder are explained the steps of the first embodiment to make thecatalyst of the invention, the method in which the zeolite is mixed withthe binder, shaped to a catalyst, then P is introduced.

As regards the zeolite of step a) containing at least one 10 membersring into the structure, one can cite the crystalline silicates. It isby way of example the MFI (ZSM-5, silicalite-1, boralite C, TS-1), MEL(ZSM-11, silicalite-2, boralite D, TS-2, SSZ-46), FER (Ferrierite, FU-9,ZSM-35), MTT (ZSM-23), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), TON (ZSM-22,Theta-1, NU-10), EUO (ZSM-50, EU-1), MFS (ZSM-57) and ZSM-48 family ofmicroporous materials consisting of silicon, aluminium, oxygen andoptionally boron.

Preferred zeolite structures are selected from the MFI, MTT, FER, MEL,TON, MWW, EUO, MFS.

In an embodiment, the zeolite is ZSM-5 with Si/Al atomic ratio rangingfrom 11 to 30, which has been made without direct addition of organictemplate.

In an embodiment, the zeolite is MFI zeolite with Si/Al atomic ratioranging from 30 to 200.

The three-letter designations “MFI” and “MEL” each representing aparticular crystalline silicate structure type as established by theStructure Commission of the International Zeolite Association. Examplesof a crystalline silicate of the MFI type are the synthetic zeoliteZSM-5 and silicalite and other MFI type crystalline silicates known inthe art. Examples of a crystalline silicate of the MEL family are thezeolite ZSM-11 and other MEL type crystalline silicates known in theart. Other examples are Boralite D and silicalite-2 as described by theInternational Zeolite Association (Atlas of zeolite structure types,1987, Butterworths). The preferred crystalline silicates have pores orchannels defined by ten oxygen rings.

Crystalline silicates are microporous crystalline inorganic polymersbased on a framework of XO₄ tetrahedra linked to each other by sharingof oxygen ions, where X may be trivalent (e.g. Al, B, . . . ) ortetravalent (e.g. Ge, Si, . . . ). The crystal structure of acrystalline silicate is defined by the specific order in which a networkof tetrahedral units are linked together. The size of the crystallinesilicate pore openings is determined by the number of tetrahedral units,or, alternatively, oxygen atoms, required to form the pores and thenature of the cations that are present in the pores. They possess aunique combination of the following properties: high internal surfacearea; uniform pores with one or more discrete sizes; ionexchangeability; good thermal stability; and ability to adsorb organiccompounds. Since the pores of these crystalline silicates are similar insize to many organic molecules of practical interest, they control theingress and egress of reactants and products, resulting in particularselectivity in catalytic reactions. Crystalline silicates with the MFIstructure possess a bidirectional intersecting pore system with thefollowing pore diameters: a straight channel along [010]:0.53-0.56 nmand a sinusoidal channel along [100]:0.51-0.55 nm. Crystalline silicateswith the MEL structure possess a bidirectional intersecting straightpore system with straight channels along [100] having pore diameters of0.53-0.54 nm.

In an embodiment, the zeolite is pretreated by steam. The pretreatmentis performed in the range 420 to 870° C., more preferably in the range480 to 800° C. The water partial pressure may range from 13 to 100 kPa.The steam atmosphere preferably contains from 5 to 100 vol % steam withfrom 0 to 95 vol % of a gas, preferably nitrogen or air. The steamtreatment is preferably carried out for a period of from 0.01 to 200hours, more preferably from 0.05 to 50 hours, still more preferably forat least 0.1 hour and in a preferred way from 0.1 to 50 hours and in amore preferred way from 0.5 to 50 hours and still more preferred 1 to 50hours.

The steam treatment tends to reduce the amount of tetrahedral aluminiumin the crystalline silicate framework by forming alumina. Preferably,the amount of residual tetrahedral Al in the zeolite is between 60 to95%. This value can be estimated by ²⁷Al MAS NMR or TPD NH3. Optionallysaid alumina can be removed by leaching with an acid.

In an embodiment, the ZSM-5 with Si/Al atomic ratio ranging from 11 to30, which has been made without direct addition of organic template, ispretreated by steam.

Additionally, if during the preparation of the zeolite alkaline oralkaline earth metals have been used, the molecular sieve might besubjected to an ion-exchange step. Conventionally, ion-exchange is donein aqueous solutions using ammonium salts or inorganic acids.

In an embodiment, the zeolite is subjected to dealumination such asabout 10% by weight of the aluminium is removed. Such dealumination canbe done by any conventional techniques known per se but isadvantageously made by a steaming optionally followed by a leaching. Thecrystalline silicate having a ratio Si/Al of at least about 30 to 200can be synthetized as such or it can be prepared by dealumination of acrystalline silicate with lower initial Si/Al ratio.

As regards step b), and the binder, it is selected so as to be resistantto the temperature and other conditions employed in the processes usingthe catalyst. The binder can be an inorganic material selected fromsilica, metal silicates, zirconia, borates, alumina, silica-aluminas,phosphates, for example amorphous aluminophosphates, calcium phosphates,clays, metal oxides such as Zr0₂ and/or metals, or gels includingmixtures of silica and metal oxides.

In an embodiment, the binder is substantially neutral (inert) and it isselected from inorganic material selected from silica, non-acid alumina,amorphous aluminophosphates, metalphosphates, clays or a mixture ofthereof. The neutral nature of the binder allow limiting secondaryreactions leading to formation of heavy oxygenates and hydrocarbons,etane, acetaldehyde etc.

A particularly preferred binder for the catalyst of the presentinvention comprises silica. The relative proportions of the finelydivided crystalline silicate material and the inorganic oxide of thebinder can vary widely.

Non-limiting examples of silicon sources include silicates, precipitatedsilicas, for example, Zeosil range available from Rhodia, fumed silicas,for example, Aerosil-200 available from Degussa Inc., New York, N.Y.,silicon compounds such as tetraalkyl orthosilicates, for example,tetramethyl orthosilicate (TMOS) and tetraethylorthosilicate (TEOS),colloidal silicas or aqueous suspensions thereof, for exampleLudox-HS-40 sol available from E.I. du Pont de Nemours, Wilmington,Del., silicic acid, alkali-metal silicate, or any combination thereof.

Other suitable forms of amorphous silica include silica powders, such asUltrasil VN3SP (commercially available from Degussa).

Other non-limiting examples of a suitable solid silica source arespecial granulated hydrophilic fumed silicas, mesoporous silica and highsurface area precipitated silica SIPERNAT from Evonik, HiSil 233 EP(available from PPG Industries) and Tokusil (available from TokuyamaAsia Pacific).

In addition, suitable amorphous silica sources include silica sols,which are stable colloidal dispersions of amorphous silica particles inan aqueous or organic liquid medium, preferably water.

Non-limiting examples of commercially available silica sols includethose sold under the tradenames Nyacol (available from Nyacol NanoTechnologies, Inc. or PQ Corp.), Nalco (available from Nalco ChemicalCompany), Ultra-Sol (available from RESI Inc), Ludox (available fromW.R. Grace Davison), NexSil (available from NNTI).

Many silica sols are prepared from sodium silicate and inevitablycontain sodium. It is, however, found that the presence of sodium ionscan cause sintering of the silica body at high temperature and/or affectcatalytic performance. Therefore, if silica sols containing sodium areused, a step of ion exchange may be required in order to reduce orremove sodium. To avoid carrying out ion exchange steps, it isconvenient to use silica sols that contain very little or, ideally, nodetectable traces of sodium and have a pH value of less than 7. Mostpreferably, the silica sol used in the process is slightly acidic withor without polymeric stabilizers. Non limiting examples of silica solsthat contain no detectable traces of sodium include Bindzil 2034DI,Levasil 200, Nalco 1034A, Ultra-Sol 7H or NexSil 20A.

In some case, silica dispersion prepared with alkylammonium might beuseful. Non-limiting examples of commercially low sodium silica solsstabilized by ammonia or alkylammonium cations include LUDOX TMA(available from W.R. Grace Davison) or VP WR 8520 from Evonik.

The silica sols with higher SiO₂ content than 30% and even up to 50 wt%, for example W1250, W1836, WK341, WK7330 from Evonik are particularlypreferred.

The preferred source of silicon is a silica sol or a combination ofsilica sol with precipitated or fumed silica.

Types of silica sols used to form a bound catalyst for use in alcoholdehydration process are commercially available as aquasols or organosolscontaining dispersed colloidal silica particles. For example, sodiumsilicate can be used as a silica sol. Otherwise, a silica gel, fumed orpyrogenic silica may also be used to provide a silica binder in themolecular sieve catalyst. Silicic acid is another possible source ofsilica. Advantageously, the binder contains low amount of sodium below1000 ppm.

Clays are known to be essentially inert under a wide range of reactionconditions. Suitable clays include commercially available products suchas kaolin, kaolinite, montmorillonite, attapulgite, saponite, andbentonite. These clays can be used as mined in their natural state, orthey may also be employed in highly active forms, typically activated byan acid treatment procedure. Commercial suppliers of these clays includeThiele Kaolin Company, American Colloidal Co., and others.

Clays contribute to strength as a binder enhancing the attritionresistance properties of the catalyst particles, and clays incombination with binders contribute to the hardness of the particles.Clays also start as small particles and have a higher density, such thatwhen combined with the molecular sieve and binder provide for denserparticles, imparting the desirable characteristic of higher density.

Clays are used in this process to form a hardened product include, butare not limited to, kaolin, kaolinite, montmorillonite, saponite,bentonite, and halloysite.

In an embodiment, the binder material is often, to some extent, porousin nature and may be effective to promote the desired conversion ofethanol to ethylene. The binder might be a single amorphous entity, or ablend of two or more individual amorphous compounds.

In a related embodiment, the catalyst, binder+zeolite, has a volume ofthe pore between 30 Å and 1000 Å of at least 0.25 cc/g, advantageouslybetween 0.25 and 1 cc/g preferably at least 0.26 cc/g, the mostpreferable between 0.27-0.92 cc/g. “cc” means cm3.

In an embodiment, the binder material possesses acid properties and mayalso promote conversion of the ethanol.

In referring to these types of binders that may be used, it should benoted that the term silica-alumina does not mean a physical mixture ofsilica and alumina but means an acidic and amorphous material that hasbeen cogelled or coprecipitated. This term is well known in the art andis described, for example, in U.S. Pat. No. 3,909,450 BI; U.S. Pat. No.3,274,124 B1 and U.S. Pat. No. 4,988,659 B I. In this respect, it ispossible to form other cogelled or coprecipitated amorphous materialsthat will also be effective as either binder or filler materials. Theseinclude silica-zirconias, silica-thorias, silica-berylias,silica-titanias, silica-alumina-thofias, silica-alumina-zirconias,alurninophosphates, mixtures of these, and the like.

In another embodiment, catalyst contains alumina materials such asaluminum oxyhydroxide, γ-alumina, boehmite, diaspore, and transitionalaluminas such as α-alumina, β-alumina, γ-alumina, δ-alumina, δ-alumina,κ-alumina, and ρ-alumina, aluminum trihydroxide, such as gibbsite,bayerite, nordstrandite, doyelite, and mixtures thereof.

It is desirable to provide a catalyst having a good crush strength. Thisis because in commercial use, it is desirable to prevent the catalystfrom breaking down into powder-like materials. Such oxide binders havebeen employed normally only for the purpose of improving the crushstrength of the catalyst.

The catalyst composition may be prepared, as indicated above, by any ofthe methods described in the art. Advantageously, however, the catalystparticles are combined with the binder material initially by dry-mixing,then in a liquid, preferably water, preferably with a plasticizer, toyield a paste.

As plasticizer (shaping additive), there may be mentioned one that willbe decomposed during any subsequent heat treatment, e.g., calcination.Suitable materials for this purpose include, for example, alkylatedcellulose derivatives, hydroxyethylcellulose (HEC), tylose, ammoniumalginate, polyvinyl pyrrolidone, glycerol, and polyethylene glycol.

In addition to enhancing the catalyst strength properties, the bindermaterial allows the molecular sieve crystallite powder to be bound intolarger particle sizes suitable for commercial catalytic processes. Theformulation of the mixture b) may be formed into a wide variety ofshapes including extrudates, spheres, pills, and the like.

The uniformly mixed paste may subsequently be shaped, for example byspray drying to yield microspheres, pelletizing or, preferably, byextrusion.

The paste is then extruded, for example in a piston extruder, intostrings, for example cylindrical, dried, again calcined, and choppedinto pieces of a desired length.

As regards the proportions of the zeolite, the one or more binders andshaping additives, advantageously the proportion of the zeolite is from5 to 95 w % of the catalyst. The catalyst comprises the zeolite and atleast a component selected among one or more binders and shapingadditives. The amount of zeolite which is contained in the catalystranges more advantageously from 15 to 90 weight percent of the totalcatalyst, preferably 20 to 85 weight percent of the catalyst.

Once the molecular sieve catalyst composition is shaped, and in asubstantially dry or dried state, a heat treatment, for examplecalcination, is advantageously performed to harden and/or activate thecomposition. Therefore the heat treatment is preferably carried out at atemperature of at least 400° C., for a period of from 1 to 48 hours.Calcination may be carried out, for example, in a rotary calciner, fluidbed calciner, or a batch oven.

As regards the Ion-exchange of step c), purpose is to get advantageouslya formulated zeolitic molecular sieve with an inert binder beforesubjecting in a contact with a phosphatation agent having less than than1000 wppm of alkali & alkali-earth metals, Na, K, Fe as well as lessthan 200 ppm of red-ox & noble elements such as Zn, Cr, Rh, Mn, Ni, V,Mo, Co, Cu, Cd, Pt, Pd, Ir, Ru, Re. This may achieved by an optionalback ion-exchange step known per se.

Although in principle mixing with the binder and ion exchange may becarried out in any order, advantageously ion exchange is performed aftershaping but before phosphorus introduction.

The ion exchange step is performed on shaped calcined catalyst before orafter the steaming step d). In an embodiment, the catalyst comprises amolecular sieve has been treated to reduce alkali metal content to lessthan 100 ppm.

As regards the steaming of step d), it is also known as the pre-steamingby reference to the final steaming of step i). The treatment isperformed in the range 420 to 870° C., more preferably in the range 480to 800° C. The water partial pressure may range from 13 to 100 kPa. Thesteam atmosphere preferably contains from 5 to 100 vol % steam with from0 to 95 vol % of a gas, preferably nitrogen or air. The steam treatmentis preferably carried out for a period of from 0.01 to 200 hours, morepreferably from 0.05 to 50 hours, still more preferably for at least 0.1hour and in a preferred way from 0.1 to 50 hours and in a more preferredway from 0.5 to 50 hours and still more preferred 1 to 50 hours.

The steam treatment tends to reduce the amount of tetrahedral aluminiumin the crystalline silicate framework by forming alumina. Preferably,the amount of residual tetrahedral Al in the zeolite is between 60 to95%. This value can be estimated by ²⁷Al MAS NMR or TPD NH₃.

As regards the introduction of P of step e), said introduction ofphosphorus can be performed under reduced or atmospheric pressure attemperature from 10 to 400° C. A non-limiting source of phosphorus canbe provided in aqueous or non-aqueous medium.

In an embodiment, the non-aqueous medium is selected from the groupcontaining ethanol, methanol or other alcohols.

The preferred techniques are impregnation and chemical vapourdeposition.

These techniques imply a minimum waste to treat and allow maintainingsubstantially all phosphorus on the catalyst.

In an embodiment, the catalyst precursor is treated by a source ofphosphorus injected into a steam flow. In this case, the phosphatationis performed under mild steaming condition with a steam flow containingphosphorus at 100-400° C.

In an embodiment, the phosphorus is introduced by a treatment of thecatalyst precursor (zeolite+binder) in a solution containing a source ofphosphorus at temperature 25-100° C. for 0.1-96 h followed by filteringor evaporation.

In an embodiment amount of said acid solution containing P isadvantageously between 2 and 10 liters per kg of zeolite plus binder. Atypical period is around 0.5 to 24 hours. Advantageously the aqueousacid solution containing the source of P has a pH of 3, advantageously2, or lower. Advantageously said aqueous acid solution is phosphorusacids, a mixture of phosphorus acids and organic or inorganic acid ormixtures of salts of phosphorus acids and organic or inorganic acids.The phosphorus acids or the corresponding salts can be of the phosphate([PO₄]³⁻, being tribasic), phosphite ([HPO₃]²⁻, being dibasic), orhypophosphite ([H₂PO₂]¹⁻, being monobasic), type. Of the phosphate typealso di or polyphosphates ([P_(n)O_(3n+1)]^((n+2)−)) can be used. Thecontact of the zeolite+binder with the P containing component can bemade under reflux conditions.

In a preferred embodiment the incipient wetness impregnation techniquesis used. In this the phosphorus is introduced via impregnation using alimited amount of liquid water which is subjected to a contact withcatalyst. This method is also known as the dry impregnation.

Incipient wetness (IW) or incipient wetness impregnation (IWI) is acommonly used technique for the synthesis of heterogeneous catalysts.Typically, the precursor (phosphorus-containing compounds) is dissolvedin an aqueous or organic solution. The volume of solution, which is usedfor dissolution of the precursor, is substantially the same as the porevolume of catalyst precursor containing both binder and zeolite. Thenthe precursor-containing solution is added to a catalyst precursor.Capillary action draws the solution into the pores. The catalyst canthen be dried and calcined to drive off the volatile components withinthe solution, depositing the phosphorus on the catalyst surface.

The sample before impregnation can be dried or calcined. Theimpregnation could be performed at room or elevated temperature.

The adsorption capacity is typically measured by impregnating the driedextruded zeolite with water until the zeolite was completely wet.Weighing the zeolite before and after impregnation gives the absorptioncapacity:

${{Absorption}\mspace{14mu}{capacity}\mspace{14mu}(\%)} = {\frac{{{weight}\mspace{14mu}{after}\mspace{14mu}{impregantion}} - {{dry}\mspace{14mu}{weight}}}{{dry}\mspace{14mu}{weight}}*100}$

In an embodiment, H3PO4 solution is used for impregnation.

Advantageously, a mixture of H3PO4 with their ammonium salts providing apH of the aqueous solution higher than 2.0 is used for impregnation

In an embodiment, the sources of phosphorus are substantially metal freecomponents, for example H3PO4, ammonium phosphates or organicP-compounds. “substantially metal free” means a metal proportion withhas no adverse effect on the P introduction. By way of example thisproportion can be below 1000 wppm.

The amount of phosphorus on the catalyst can be from 0.5 to 30 wt %, butpreferably from 0.5 to 9 w %.

In an embodiment, the phosphatation step is performed before orsimultaneously with introduction of metal.

As regards step f), the introduction of metal, it can be one or moremetals. Advantageously said metals are selected among alkaline earth orrare earth metals. The alkaline earth or rare earth metal M ispreferably selected from one or more of: Mg, Ca, Sr, Ba, La, Ce. Morepreferably, M is an alkaline earth metal. Most preferably, M is Ca.Particularly in the case of P-modification via steaming and leaching, Mcan be a rare earth metal such as La and Ce. Advantageously the metal isintroduced in a soluble form.

The M-containing component is preferably in the form of an organiccompound, a salt, hydroxide or oxide. The compound is preferably in asolubilized form when bringing it into contact with the molecular sieve.Alternatively, the solution of the M-containing compound can be formedafter bringing the molecular sieve in contact with said compound.

Possible M-containing compounds include compounds such as sulphate,formate, nitrate, acetate, halides, oxyhalides, borates, carbonate,hydroxide, oxide and mixtures thereof. One can cite calcium carbonate.

Those M-containing compounds, which are poorly water-soluble, can bedissolved to form a well-solubilized solution by heating and/or bymodifying the pH of the solution by addition of phosphoric, acetic ornitric acid or corresponding ammonium salts of said acids.

As regards step g), a washing step can be envisaged. In accordance withthe present invention, the catalyst is treated with water for a periodof time from 0.1 to 48 hours, preferably for a period of time from about0.5 to 36 hours and most preferably from about 1 to 24 hours. The waterwas at a temperature between about 20° C. and 180° C., preferablybetween about 20° C. and 100° C. and most preferably between about 25°C. and 60° C. By way of example the water can be at 30° C. Following thewater treatment, the catalyst may be dried at about >60° C. Optionally,the water can contain at least one dissolved solid selected from thegroup consisting of ammonium chloride, ammonium phosphate, ammoniumsulfate, ammonium acetate, ammonium carbonate, ammonium nitrate andmixtures thereof.

As regards step h), said calcination can be made in air or an inert gas,typically at a temperature of from 350 to 900° C. for a period of from 1to 48 hours. Optionally the air or an inert gas may contain steam inconcentration from 10 to 90 vol %.

As regards step i), it can be performed in the range 420 to 870° C.,preferably in the range 480 to 870° C., preferably from 625 to 870° C.and more preferably from 700 to 800° C., still more preferably in therange 720 to 800° C. Alternatively it can be performed in the range 420to 600° C., preferably 420 to 580° C. The water partial pressure mayrange from 13 to 100 kPa. The steam atmosphere preferably contains from5 to 100 vol % steam with from 0 to 95 vol % of a gas, preferablynitrogen or air. The steam treatment is preferably carried out for aperiod of from 0.01 to 200 hours, preferably from 0.05 to 50 hours, morepreferably for at least 0.1 hour and in a preferred way from 0.1 to 50hours, and in a more preferred way from 0.5 to 50 hours and still morepreferred 1 to 50 hours.

In said first embodiment, in a first process way, advantageously two ormore of the following features can be combined:

at least among said steaming of step d) and the steaming of step a) oneis mandatory,

introduction of P is made by dry impregnation or chemical vapordeposition,

at step f), optionally introduction of a metal, advantageously calcium.

In said first embodiment, in a second process way, advantageously two ormore of the following features can be combined:

at least among said steaming of step d) and the steaming of step a) oneis mandatory,

at step f), optionally introduction of a metal, advantageously calcium,

step i) is performed by steaming at a steaming severity (X) of at leastabout 2.

The above-described “steaming severity (X)” is an important, measurableand critical definition of treatment conditions for the steps d) whichare useful in the instant invention.

“About” means that it could be slightly under 2. As explained hereunderthe severity describes conditions of steaming to achieve adealumination.

The matter is that the results of the steaming is a function of thenature of catalyst (type of zeolite, type of binder, Si/Al ratio,crystal size, crystallinity, structure defects, the presence of occludedcontaminants etc) as well as of conditions of the treatment used. It isclear that the minimum severity is not an absolute value, consideringthe above parameters it can vary from a catalyst to another. The manskilled in the art can easily determine the minimun severity. To besure, he can, by way of example, extend the duration of treatment and/orincrease the temperature.

The critical parameters for the treatment include mainly steam partialpressure, temperature and duration of the treatment. If the objects ofthe treatment were similar nature the effect of the treatment is only afunction of the “steaming severity”.

A steaming or a hydrothermal treatment of the zeolite above 500° C.leads to a delumination of the framework. A degree of dealuminationcould be measured by ²⁷Al, ²⁹Si MAS NMR, by acidity measurement (likeTPD NH₃) or by any other means, which are well known in the prior art. Arate of the dealumination is defined mainly by mentioned aboveparameters, namely, steam partial pressure, temperature and duration ofthe treatment.

Thus, the “steaming severity (X)” is defined as a ratio of thedealumination rates between an experimental condition vs a standardcondition.

Steaming performed at 600° C., in 100% of steam at atmospheric pressureduring 2 h is selected as a standard condition for this invention.

The rate of dealumination (V) for the catalyst of invention is given byequation:V÷Const×P(H₂O)^1.5×t _(st)/EXP(−0.03×T _(st)),where P(H₂O)—steam partial pressure (P/Patm); T_(st)—steamingtemperature in ° C.; t_(st)—time in hours (duration) of treatment and ÷means proportional.X(The steaming severity)=V _(experimental condition) /V_(standard condition)

This equation is valid in a steaming interval from 500° C. to 760° C.

So, the steaming severity value could be achieved even at lowertemperature relative to the used in standard condition but for a highertime of steaming.

The temperature 625° C. provides roughly 2 times higher steam severityvs the standard condition at equal steam partial pressure and durationof the treatment.

If the temperature of the equilibration step is above 760° C. (out ofthe range), the duration of steaming is at least 0.1 h and the partialpressure of steam is at least 0.01 bar.

Advantageously in said first embodiment, second process way, thetemperature of the equilibration step is in the range 625 to 870° C.preferably from 625 to 870° C. and more preferably from 700 to 800° C.still more preferably in the range 720 to 800° C.

Hereunder are explained the steps of the second embodiment to make thecatalyst of the invention in which P is introduced in the zeolite, the Pmodified zeolite is mixed with the binder, then shaped to a catalyst.

Step a) is the same as in the first embodiment.

As regards the Ion-exchange of step a), purpose is to get advantageouslya zeolite before subjecting in a contact with a phosphatation agenthaving less than than 1000 wppm of alkali & alkali-earth metals, Na, K,Fe as well as less than 200 ppm of red-ox & noble elements such as Zn,Cr, Rh, Mn, Ni, V, Mo, Co, Cu, Cd, Pt, Pd, Ir, Ru, Re. This may beachieved by an optional back ion-exchange step known per se.

The ion exchange step is performed before the steaming of step b) ifany.

As regards the steaming of step b), it is similar to the one of step d)of the first embodiment.

As regards the introduction of P at step c), this is similar to theintroduction of P already described at step e) in the first embodimentexcepted that there is no binder.

As regards step d), and step e), as well as the proportions of zeoliteand binder this is similar to step b) already described in the firstembodiment, except that the zeolite has been P modified.

In a related embodiment, the catalyst (zeolite+binder) has a volume ofthe pore between 30 Å and 1000 Å of at least 0.25 cc/g, advantageouslybetween 0.25 and 1 cc/g preferably at least 0.26 cc/g, the mostpreferable between 0.27-0.92 cc/g. “cc” means cm3.

As regards steps f) to i), they are the same as in the first embodiment.

In said second embodiment, in a first process way, advantageously two ormore of the following features can be combined:

said steaming of step b) is mandatory,

introduction of P is made by dry impregnation or chemical vapordeposition,

at step f), optionally introduction of a metal, advantageously calcium.

In said second embodiment, in a second process way, advantageously twoor more of the following features can be combined:

said steaming of step b) is mandatory,

at step f), optionally introduction of a metal, advantageously calcium,

step i) is performed by steaming at a steaming severity (X) of at leastabout 2.

Advantageously in said second embodiment, second process way, thetemperature of the equilibration step is in the range 625 to 870° C.preferably from 625 to 870° C. and more preferably from 700 to 800° C.still more preferably in the range 720 to 800° C.

As regards the dehydration process to convert an alcohol into an olefin,this process has been described in a lot of patent applications. One cancite WO/2009/098262, WO/2009/098267, WO/2009/098268 and WO 2009/098269,the content of which is incorporated in the present application. Thealcohol is any alcohol provided it can be dehydrated to thecorresponding olefin. Advantageously the alcohol has two or more carbonatoms. The corresponding olefin is an olefin having the same number ofcarbons as the alcohol. By way of example mention may be made ofalcohols having from 2 to 10 carbon atoms. Advantageously the inventionis of interest for ethanol, propanol, butanol and phenylethanol.

As regards the cracking of olefins, more precisely the present inventionrelates to a process for cracking an olefin-rich hydrocarbon feedstockwhich is selective towards light olefins in the effluent. In particular,olefinic feedstocks from refineries or petrochemical plants can beconverted selectively so as to redistribute the olefin content of thefeedstock in the resultant effluent. Said cracking of an olefin-richfeedstock is often referred in the following description and claims asOCP (Olefin Cracking Process). As regards the hydrocarbon feedstockcontaining one or more olefins sent to the OCP reactor, in accordancewith the present invention, cracking of olefins is performed in thesense that olefins in a hydrocarbon stream are cracked into lighterolefins and selectively into propylene. The feedstock and effluentpreferably have substantially the same olefin content by weight.Typically, the olefin content of the effluent is within ±15 wt %, morepreferably ±10 wt %, of the olefin content of the feedstock. Thefeedstock may comprise any kind of olefin-containing hydrocarbon stream.The feedstock may typically comprise from 10 to 100 wt % olefins andfurthermore may be fed undiluted or diluted by a diluent, the diluentoptionally including a non-olefinic hydrocarbon. In particular, theolefin-containing feedstock may be a hydrocarbon mixture containingnormal and branched olefins in the carbon range C₄ to C₁₀, morepreferably in the carbon range C₄ to C₆, optionally in a mixture withnormal and branched paraffins and/or aromatics in the carbon range C₄ toC₁₀. Typically, the olefin-containing stream has a boiling point of fromaround −15 to around 180° C. With regards to the OCP process, saidprocess is known per se. It has been described in EP 1036133, EP1035915, EP 1036134, EP 1036135, EP 1036136, EP 1036138, EP 1036137, EP1036139, EP 1194502, EP 1190015, EP 1194500 and EP 1363983 the contentof which are incorporated in the present invention.

As regards the MTO, said process produces light olefins such as ethyleneand propylene as well as heavy hydrocarbons such as butenes. Said MTOprocess is the conversion of methanol or dimethylether by contact with amolecular sieve which can be a P modified zeolite.

As regards the alkylation of aromatic compounds with olefins andalcohols, said process produces para-xylene, ethylbenzenes and cumene.Alkylation of aromatic, for example, toluene methylation has been knownto occur over acidic catalyst, particularly over zeolite or zeolite-typecatalyst. In particular, ZSM-5-type zeolite, zeolite Beta andsilicaaluminophosphate (SAPO) catalysts have been used for this process.

One skilled in the art will also appreciate that the olefins made by thedehydration process of the present invention can be, by way of example,polymerized. When the olefin is ethylene it can be, by way of example,

polymerized to form polyethylenes,

dimerized to butene and then isomerised to isobutene, said isobutenereacting with ethanol to produce ETBE,

dimerized to butane followed by reacting with ethylene via methatesis toproduce propylene;

converted to propylene over metal, acid or bifunctional catalyst, usedfor alkylation of benzene to form ethyl-benzene,

dimerised to 1-butene, trimerised to 1-hexene or tetramerised to1-octene, said alpha-olefins comonomers are further reacted withethylene to produce polyethylene

dimerised to 1-butene, said 1-butene is isomerised to 2-butene and said2-butene is further converted with ethylene by metathesis reaction intopropylene and said propylene can be polymerised to polypropylene,

converted to ethylene oxide and glycol or

converted to vinyl chloride.

The present invention relates also to said polyethylenes, polypropylene,propylene, butene, hexane, octene, isobutene, ETBE, vinyl chloride,ethylene oxide and glycol.

When the olefin is propylene it can be, by way of example,

polymerized to form polypropylene,

used for alkylation of aromatics etc. . . .

-   -   etc. . . .

EXAMPLES Example 1

A sample of zeolite ZSM-5 (Si/Al=12) in NH4-form (contained 250 ppm ofNa & synthesized without template) was blended with a silica binder in aratio 80:20 followed by addition of extrusion additives and shaping. Afinal Na content in the catalyst was 320 ppm.

The extruded sample was dried for 2 h at 140° C., calcined for 2 h at600° C. followed by steaming at 625° C. for 2 h in 50% steam (steamingseverity 0.75). The sample is hereinafter identified as sample A.

287 g of steamed solid (sample A) was incipient wetness impregnated withan aqueous solution containing 27.08 g of phosphoric acid. Theimpregnated solid was dried for 16 h at 110° C.

Then, the phosphated sample was incipient wetness impregnated with asolution of calcium nitrate obtained by dissolution of 7.18 g of calciumcarbonate. The impregnated solid was dried for 16 h at 110° C.

Resulted catalyst containing about 2.6 wt % of phosphorus and 0.8% ofcalcium was steamed at 750° C. for 1 h in 100% of steam (steamingseverity 45). The sample is hereinafter identified as sample B.

FIG. 1 shows that the ²⁷Al MAS NMR spectrum of phosphated sample B isdominated by a relatively sharp and intensive resonance at 39 ppmrepresenting the AlPO phase. The position of this signal is verydifferent from the extra framework aluminum phase observed on thesteamed sample A (signals at 30 and 2 ppm). The fact that the aluminumfree-binder was used, demonstrates a formation of AlPO-containingzeolite. The area of the signal at 35-45 ppm is about 45% of totalAl-species in the spectrum of sample B.

MAS NMR spectra are measured after the dehydration of the zeolite.Before the measurement of the ²⁷Al MAS NMR spectra, all samples werefully hydrated in a desiccator with a saturated NH₄NO₃ solution for 24 hto avoid as much as possible detection failures of the Al species due totheir asymmetrical environments. After dehydration, the sample can betransferred in situ into the conventional NMR rotor, and sealed withoutcontacting air or moisture.

(Dehydration of Ethanol)

Catalyst tests were performed on 1 ml of catalyst grains (catalyst B,35-45 mesh) loaded in a tubular reactor with internal diameter 11 mm. Amixture 25 wt % EthOH/75 wt % H₂O was subjected to a contact withcatalyst described in the example I in a fixed bed reactor at 380° C.,WHSV=7 h⁻¹ P=2 bara. The results are given in table 1 hereunder. Thevalues are the weight percents on carbon basis.

TABLE 1 Sample B P (bara) 2 T (° C.) 380 WHSV (h⁻¹) 7 EtOH conversion (%wt CH2) 99.9 DEE 0.0 Acetaldyde 0.16 EtOH 0.1 Yield on C-basis (% wtCH2) CH4 0.00 C2 0.08 C2 = 98.7 C3 = 0.2 C4+ olef 0.6 Unknown 0.12Selectivity on C-basis (% wt CH2) C2 = 98.8 C2's cut purity (%) 99.92

Example 2

A sample of zeolite ZSM-5 (Si/Al=12) in NH4-form (contained 250 ppm ofNa & synthesized without template) was blended with a binder containingsilica and kaolin in a ratio 70:10:20 followed by addition of extrusionadditives and shaping.

The extruded sample was dried for 2 h at 140° C., calcined for 10 h at600° C. followed by steaming at 550° C. for 6 h in 100% steam. Thesample is hereinafter identified as sample C.

Steamed solid (sample C) was incipient wetness impregnated with anaqueous solution of phosphoric acid to introduce about 3 wt % ofphosphorus to the catalyst. The impregnated solid was dried for 16 h at110° C.

Then, the phosphated sample was incipient wetness impregnated with asolution of calcium nitrate obtained by dissolution of calcium carbonateto introduce about 1 wt % of calcium to the solid. The impregnated solidwas dried for 16 h at 110° C.

Resulted catalyst containing 2.94 wt % of phosphorus and 0.8% of calciumwas steamed at 750° C. for 2 h in 100% of steam (steaming severity 90).The sample is hereinafter identified as sample D.

FIG. 2 shows that the phosphated sample D shows relatively sharp andintensive resonance at 39 ppm representing the AlPO phase.

Catalytic Performances

Catalyst tests were performed on 0.8 g of catalyst grains (catalyst B,35-45 mesh) loaded in the tubular reactor. The feedstock which containssubstantially non cyclic olefins C4 (˜60%) was subjected to catalyticcracking in the presence of catalyst in a fixed bed reactor atT_(in)-550° C., WHSV=16 h⁻¹, P=1.5 bara. The results are in table 2. Thevalues in the table 1 are the average catalyst performance for 1-10hours-on-stream given in weight percents on carbon basis.

The data given below illustrate good cracking activity and highselectivity of the P-zeolite (sample D) in C4 olefins conversion topropylene and ethylene.

TABLE 2 Sample D P (bara) 1.5 T_(in) (° C.) 550 WHSV (h⁻¹) 16 C4 olefinsconversion, % 65.4 Purity C3's, % 94.9 Yield on C-basis, % Methane 0.07Aromatics 1.2 Propane 1.0 Ethylene 3.5 Propylene 19.5

The invention claimed is:
 1. A catalyst comprising: a phosphorusmodified zeolite, wherein the zeolite comprises at least one ten memberring in the structure thereof; wherein the phosphorus modified zeolitehas partly an ALPO structure, wherein the ALPO structure is determinedby a signal between 35-45 ppm in ²⁷Al MAS NMR spectrum; a binder; andoptionally one or more metals.
 2. The catalyst of claim 1, wherein thezeolite is MFI, MTT, FER, MEL, TON, MWW, EUO, or MFS.
 3. The catalyst ofclaim 1, wherein the zeolite is ZSM-5 with Si/Al atomic ratio rangingfrom 11 to 30, and wherein the zeolite has been made without directaddition of organic template.
 4. The catalyst of claim 1, wherein thezeolite is MFI with Si/Al atomic ratio ranging from 30 to
 200. 5. Thecatalyst of claim 1, wherein an amount of phosphorus on the catalyst isfrom 0.5 to 30 wt %.
 6. The catalyst of claim 1, wherein an amount ofphosphorus on the catalyst is from 0.5 to 9 w %.
 7. The catalyst ofclaim 1, wherein the catalyst comprises the one or more metals.
 8. Thecatalyst of claim 7, wherein the one or more metals are alkaline earthor rare earth metals M.
 9. The catalyst of claim 7, wherein the one ormore metals comprise Mg, Ca, Sr, Ba, La, Ce, or combinations thereof.10. The catalyst of claim 1, wherein the catalyst has a volume of poresbetween 30 Å and 1000 Å of at least 0.25 cc/g.
 11. The catalyst of claim1, wherein the binder is substantially free of alumina or alumina salts.12. The catalyst of claim 1, wherein most of the Al atoms in the AlPO₄phase originate from the zeolite or from a part of the binder.
 13. Thecatalyst of claim 12, wherein the part of the binder is clays.